Humboldt County Bridge Report Card
Humboldt County scores 76 out of 100 on BridgeLookup's Bridge Condition Exposure Score, based on FHWA National Bridge Inventory records.
Humboldt County, California
Humboldt County has 399 bridges in the National Bridge Inventory, with 21 rated poor and 16 rated scour-critical. Its poor-condition share of 5.3% is above the 4.9% statewide average. Poor-condition bridges carry about 34,427 daily vehicle crossings.
Quote-Ready Local Facts
Copyable Facts for Reporters
BridgeLookup.com gives Humboldt County a Bridge Condition Exposure Score of 76/100 (C). The county has 399 bridges in the National Bridge Inventory, including 21 in poor condition and 16 rated scour-critical. Poor-condition bridges carry about 34,427 daily vehicle crossings. Poor condition does not mean unsafe; bridges judged unsafe are closed or restricted by transportation agencies.
How the Score Breaks Down
| Factor | Weight | County Value | Penalty |
|---|---|---|---|
| Poor-condition bridge share | 40 | 5.3% | 10.5 |
| Poor-condition traffic exposure | 25 | 2.4% of measured traffic | 1.8 |
| Scour-critical bridge share | 20 | 4.0% | 8.0 |
| Average age vs national baseline | 10 | 58 years vs 48 nationally | 3.9 |
| Traffic-data completeness | 5 | 1,408,608 measured daily crossings | 0.0 |
Score = 100 minus weighted penalties. The score is a comparative research signal, not an official safety rating. Read the full methodology.
County Comparisons
| County Poor-Condition Share | 5.3% |
| State Poor-Condition Share | 4.9% |
| National Poor-Condition Share | 6.7% |
| County Scour-Critical Share | 4.0% |
| Average Bridge Age | 58 years |
| Poor-Condition Traffic Exposure | 34,427 vehicles/day |
Bridges to Watch
Top Bridges to Watch in Humboldt County
| Bridge | Reason | Condition | Daily Traffic | Year Built |
|---|---|---|---|---|
| Zenia Bluff RD over South Dobbyn Creek | Poor condition + traffic exposure | Poor | 85 | 1949 |
| 33007: Butte Creek over Butte Creek | Poor condition + traffic exposure | Poor | 50 | 1980 |
| Grasshopper Lkt RD over Squaw Creek | Poor condition + traffic exposure | Poor | 1 | 1983 |
| US Highway 101 NB over West End RD Creek Ncrra | Poor condition + traffic exposure | Poor | 17,500 | 1929 |
| U.s. Highway 101 over Dean Crk RD & Dean Creek | Poor condition + traffic exposure | Poor | 5,000 | 1967 |
| State Route 299 over Mad River | Poor condition + traffic exposure | Poor | 4,775 | 1965 |
| Humboldt Hill Road over US Highway 101 | Poor condition + traffic exposure | Poor | 3,100 | 1963 |
| State Park Road over South Fork Eel River | Poor condition + traffic exposure | Poor | 1,100 | 1969 |
| Maple Creek Road over North Fork Mad River | Poor condition + traffic exposure | Poor | 624 | 1928 |
| Hookton Road over Salmon Creek | Poor condition + traffic exposure | Poor | 486 | 1922 |
Important safety note
Poor condition does not mean a bridge is unsafe. It means at least one major component has significant deterioration and the bridge is a priority for maintenance, repair, or replacement. Bridges judged unsafe are closed or restricted by transportation agencies.